Blue Goo is a commonly accepted name for defensive nanotechnological systems. It is effectively an artificial immune system sensitized to nanotechnological aggressors. This sensitization is divided into "inclusive" or "exclusive" general designs — it either includes all nanotech except for a known-good list as a stimulus or it reacts to encounters with members of a known-bad list as a stimulus. In practice, most blue goo is a hybrid of suspected-good and known-bad lists with anything not fitting into the list or behaving in unusual manners labelled as suspicious.

Additionally, these ecologies are divided into passive and active systems. Passive systems maintain only sensory capabilities and react with the release/construction of devices only when triggered. Active ecologies, by contrast, maintain a constant level of defensive nanotechnology in and around the defended object(s). Most blue goo ecologies maintain both a constant level of defenses and multiple levels of defensive nanosystems in reserve. A "live" blue goo ecology must therefore be a highly complex organization of multiple systems. There are some generic archetypes of defensive systems.

2) Dedicated attackers: these devices, when appropriately signalled, will try to destroy targeted molecules or nanomachines or to render them inert. There are several common subtypes:

a) Gumball: this unit is designed to immobilize targets by wrapping them in an inert coating. Passive blue goo usually contains some variant of gumballs.

b) Punji pit: this type of agent violently discharges objects (often spikes or the like) on contact with a "known bad" object. The spikes can serve to impede the target's movement or to deliver a damaging kinetic attack. Punji pits appear in both active and passive systems.

c) Disassembler: the most common attack unit in active blue goo is designed to take attacking units apart before they can damage the subject (or the disassembler itself). Molecular architecture dictates that a given molecule can only be efficiently attacked by manipulators of a certain shape; the universal disassembler that can attack all materials with equal facility is at best only available to high-level transapients and at worst a myth. Blue goo systems therefore are either specialized to defend against specific nano-agents or must incorporate several varieties of disassembler.

d) Hammer-and-anvil: this agent consists of a mechanical striker (the "hammer") which, when triggered, impacts a heavily reinforced surface (the "anvil"). The intent is to trap an opposing device between the two components, thereby damaging or destroying the target. A hammer-and-anvil setup may also be designed to clamp shut on a target that it fails to destroy. Hammer-and-anvil units appear in both active and passive blue goo.

e) Hardener: this device is much like a gumball except it contracts (due to mechanical or chemical action) after it has a grip on the target. Slow contraction serves as a simple trap while sufficiently rapid contraction can damage the target. Hardeners appear mainly in passive systems.

3) Creation crèches: an essential component of any blue goo system is the assembly plant that creates new defenders as old ones are destroyed or expended. The facilities may be very small or quite large, depending on the peak needs, energy production and heat dispersal capacity of the protected system.

4) Gunk: these simple-to-construct devices consist mainly of chemical bonds that cannot be easily broken. The function of gunk is to passively "gum up" some assemblers or disassemblers. Some passive blue goo systems consist entirely of one or more varieties of gunk. Active systems may incorporate gunk units that rush to the site of a nano-attack in response to the calls of dedicated signallers.

These conglomerations of systems are commonly tiered. Normally active systems are typically signallers and attackers, and are usually much more "exclusive" than the more "inclusive" special-use passive reserves, which are only called out in case of an emergency. Crèches may also have similar tiering in their activation. A typical system will have several signalers constrained in a close proximity to the defended objects (this is often done via very low-power coded transmissions, which may also act as the power source for some or all of these devices). They may or may not have one or more fairly exclusive dedicated attacker system(s) also in use. Crèches will be used to maintain these systems at preferred levels of saturation. As the dedicated signallers increase their calls during an attack, other systems will be flushed into the environment. These often are more aggressive, "inclusive" systems, both signallers and attackers. In extremis, some systems are configured to flood the immediate area with high density "gunk" in the hopes of preventing total subversion by denying all nanotechnological devices access to the immediate area.

Nano-ecology, Nanecology - Text by Anders SandbergA distributed system of nanodevices and the structures constructed by them that self-organizes in a bottom-up manner without any central control; analogous to an ecology. Sometimes used to denote the entire nanosphere of a world, even when parts of it are under top-down control.